A program of research is proposed to investigate the dissolution of language comprehension in the aphasias and related cognitive disorders. An approach is suggested in which the semantic domain is held constant across a variety of tasks which test comprehension of several morphological, syntactic and semantic variations within that restricted semantic domain. This procedure will provide detailed profiles of comprehension abilities for a large number of patients with a variety of symptoms and lesion sites. This information will be used to identify the components of comprehension which can be impaired in conditions of focal brain damage. The emphasis in this investigation is on the pattern of dissolution and representation of sentential meaning. A central concern is the identification of the component processes that underlie the construction of sentential meanings in comprehension. A basic contention motivating the proposed investigation is that the cognitive processes involved in the comprehension of lexical items and larger semantic units (phrases and sentences) can be differentially affected by focal brain damage. An additional set of experiments is provided to test specific hypotheses concerning the locus of comprehension breakdown in particular patient types, to test the generality of patterns of dissolution obtained within the restricted domain, and to investigate additional aspects of semantic processing. These two approaches, taken together, will provide a comprehensive picture of the patterns of semantic dissolution which occur consequent to brain damage. These patterns of comprehension deficit, related to locus of damage, will supply the type of information which is needed for the development of effective therapeutic techniques to facilitate recovery of language functions.